1、Designation: F459 13Standard Test Methods forMeasuring Pull Strength of Microelectronic Wire Bonds1This standard is issued under the fixed designation F459; the number immediately following the designation indicates the year of originaladoption or, in the case of revision, the year of last revision.
2、Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods cover tests to determine the pullstr
3、ength of a series of wire bonds. Instructions are provided tomodify the methods for use as a referee method. The methodscan be used for wire bonds made with wire having a diameterof from 0.0007 to 0.003 in. (18 to 76 m).NOTE 1Common usage at the present time considers the term “wirebond” to include
4、the entire interconnection: both welds and the interven-ing wire span.1.2 These test methods can be used only when the loopheight of the wire bond is large enough to allow a suitable hookfor pulling (see Fig. 1) to be placed under the wire.1.3 The precision of these methods has been evaluated foralu
5、minum ultra-sonic wedge bonds; however, these methodscan be used for gold and copper wedge or ball bonds.21.4 These methods are destructive. They are appropriate foruse in process development or, with a proper sampling plan, forprocess control or quality assurance.1.5 A nondestructive procedure is d
6、escribed in PracticeF458.1.6 The values in SI units are to be regarded as standard.1.7 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and
7、determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3F458 Practice for Nondestructive Pull Testing of Wire Bonds3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 For the purposes of these test methods the followingfailure
8、 points are defined:3.1.2 bond-wire junction failurea rupture in the wirewithin two wire diameters of the bond and in which more than25 % of the bonded area is left on the pad after the pull test hasbeen applied.3.1.3 weld interface failurea rupture in which less than25 % of the bonded area is left
9、on the pad after the pull test hasbeen applied. See pad lifting in 6.6.3.1.4 wire span failurea rupture in the wire other than (1)at a point within two wire diameters of either bond, or (2) at thepoint at which the hook contacted the wire.4. Summary of Test Methods4.1 The microelectronic device with
10、 the wire bond to betested is held firmly in an appropriate fixture. A hook ispositioned under the wire midway between the two bonds. Thehook is then raised until the wire bond breaks. The forceapplied to the hook in order to cause failure of the wire bondis recorded. The point of failure is observe
11、d and recorded. Inthe referee method, the force in the wire on breaking iscalculated.5. Significance and Use5.1 Failure of microelectronic devices is often due to failureof an interconnection bond.Acommon type of interconnectionbond is a wire bond. These methods can assist in maintaining1These test
12、methods are under the jurisdiction of ASTM Committee F01 onElectronics and are the direct responsibility of Subcommittee F01.07 on WireBonding, Flip Chip, and Tape Automated Bonding.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 1976 as F459 76 T. Last previous
13、edition approved in 2006 asF459 06. DOI: 10.1520/F0459-13.2Harman, G. G., ”Microelectronic Ultrasonic Bonding,” NBS Special Publica-tion 400-2, pp. 94-95 and “Wire Bonding in Microelectronics,” Third Edition,McGraw Hill, 2010. Also Microelectronics Reliability 51 (2011), Special Issue onCopper bondi
14、ng.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Bo
15、x C700, West Conshohocken, PA 19428-2959. United States1control of the process of making wire bonds. They can be usedto distinguish between weak, nonadherent wire bonds andacceptably strong wire bonds. The methods are destructive.5.2 These test methods are appropriate for on-line use forprocess cont
16、rol, for purchase specifications, and for research insupport of improved yield or reliability. The referee methodshould be used for quantitative comparison of pull strengths ofwire bonds.6. Interferences6.1 Failure to center the hook along the loop between thetwo bonds or pulling in a direction not
17、lying in the planecontaining the undisturbed loop may invalidate the test since anunbalanced distribution of forces between the two bonds mayresult.6.2 Slippage of the hook along the wire span during pullingmay invalidate the test because an unbalanced distribution offorces between the two bonds may
18、 result.6.3 Careless insertion of the hook may damage either bondor wire and thus invalidate the test.6.4 The presence of vibration or mechanical shock maycause the application of an extraneous force and thus invalidatethe test.6.5 Measured bond-pull force is strongly dependent on theheight of the l
19、oop (H+h, as defined in 11.1.1) and thebond-to-bond spacing ( d, as defined in 11.1.1).6.6 For fine pitch ball bonds (60 m pitch), the bond padmay tear and lift during pull testing. Current practice is toaccept this if the pull force is acceptably high under agreedupon requirements, but note it as a
20、ppropriate. In some cases ofbad peeling, it is necessary to move the pulling hook directlyover the top of the ball bond. This should be noted.7. Apparatus7.1 Bond-Pulling MachineApparatus for measuring wire-bond pull strength with the following components:7.1.1 HookPulling hook made from a rigid wir
21、e such astungsten. The diameter of that part of the hook that contacts thewire loop should be approximately 2.5 times the diameter ofthe wire used to make the wire bond. A suggested hookconfiguration is shown in Fig. 1. The hook should appear undervisual inspection to have a smooth polished surface
22、with nosharp edges in any part of the hook that contacts the wire loop.The hook should be rigidly mounted in the pulling apparatus.7.1.2 Lifting-and-Gaging Mechanism Mechanism for ap-plying a measured vertical force to the hook. The mechanismshall incorporate a means for recording the maximum forcea
23、pplied and shall be capable of applying force at a rate constantto within 2 gf/s (20 mN/s) in the range from 1 to 30 gf/s (10 to290 mN/s) inclusive. A mechanism with a single fixed scaleshall have a maximum scale reading no greater than three timesthe nominal bond pull strength anticipated.NOTE 2Mec
24、hanisms of the dynamometer type known as “gramgages” have been found satisfactory, but currently, electronic gauges(properly calibrated using the manufacturers procedures) are morecommon.7.1.3 Microscope with Light Source Zoom microscopewith light source with a magnification range of approximately14
25、 to 60 with the eyepiece not to exceed 10, for viewingthe device under test.7.1.4 Device Holder Mechanism for holding the deviceunder test (1) in a horizontal position, for Method A, or (2) ineither a horizontal or a tipped position so that both bonds arein the same horizontal plane, for Method B. F
26、or the refereeMethod C, the device holder should provide a measurement, towithin 2, of the angle from the horizontal (which may be zero)through which the device has been tipped.7.1.5 Calibration MassesAt least five masses (weights)with mass values known to within 0.5 % sized to cover thelifting-and-
27、gaging mechanism range of force measurement,and suitably configured so that they may be supported by thepulling mechanism for calibration.8. Sampling8.1 Since the pull-test method is destructive, it shall beperformed on a sampling basis. The sample selected should berepresentative of the wire bonds
28、of interest. The size of thesample and the method of selection shall be agreed upon by theparties to the test.9. Calibration9.1 Calibrate the bond-pulling machine at the beginning ofeach series of tests, or daily if a series spans more than one day.9.2 Assemble the bond-pulling machine in the same c
29、on-figuration to be used to perform the wire-bond pull test.FIG. 1 Suggested Configuration for a Pulling HookF459 1329.3 Calibrate the lifting-and-gaging mechanism.9.3.1 For mechanisms incorporating a calibrationadjustment, either calibrate the mechanism in accordance withthe manufacturers instructi
30、ons or in accordance with theprocedure of 9.3.2.9.3.2 For mechanisms without a calibration adjustment, usethe following procedure:9.3.2.1 Select masses that will provide at least five calibra-tion points over the mechanism range.9.3.2.2 Attach a selected calibration mass to the lifting-and-gaging me
31、chanism. If a lever-arm mechanism (dynamometeror gram gage) is used, rotate the body of the gage in a mannerthat maintains the arm (carrying the hook) in a horizontalorientation.9.3.2.3 Observe and record the measured force in grams-force (millinewtons).9.3.2.4 Repeat 9.3.2.2 and 9.3.2.3 for each ca
32、libration mass(or electronic scale) selected.9.3.2.5 Plot the measured force values as a function of theforces applied by the masses. Use these results to construct acalibration curve.10. Procedures10.1 Method ADevice in Horizontal Plane:10.1.1 Place the device having the wire bond to be tested inth
33、e device holder so that the plane of the device is horizontal,as judged visually.10.1.2 Position the microscope and light source and focusthe microscope so that the wire bond to be tested is clearly seenin the microscope field.10.1.3 Position the device holder so that the wire formingthe loop of the
34、 wire bond to be tested is under the rigidlymounted pulling hook.10.1.4 While viewing the wire bond through themicroscope, maneuver the hook so that it is under the wire loopto be pulled, and adjust the hook so that it is midway betweenthe two bonds and contacting the wire loop, as judged by eye.10.
35、1.5 Activate the pulling mechanism while observing thewire bond and hook through the microscope. Continue pullinguntil there is failure.10.1.6 If the wire fails at the point of contact with the hook,record the test for that bond as invalid.10.1.7 Measure and record the force required for breakingthe
36、 wire bond. Determine and record the corrected force fromthe calibration curve if the calibration procedure of 9.3.2 wasused. Record the identification of the wire bond and theidentification of the device (substrate).10.1.8 Examine the remaining parts of the bonds and thewire span at appropriate mag
37、nification to determine the natureand location of the failure.10.1.9 Record the failure location as being one of thefollowing:10.1.9.1 First bond at the weld interface,10.1.9.2 First bond at the bond-wire junction,10.1.9.3 In the wire span,10.1.9.4 Second bond at the weld interface,10.1.9.5 Second b
38、ond at the bond-wire junction, or10.1.9.6 Other (describe: for example, pad lift-off (see 6.6).NOTE 3The operator will normally be supplied information as towhich is the first bond and which is the second bond.NOTE 4If the tester is electronic with optical placement control, thenall hook placement/p
39、ositioning is set up during the initial machinecalibration. However, failure mode determination will be evaluated by theoperator.10.2 Method BDevice in Tipped Plane:10.2.1 Place the device having the wire bond to be tested ina device holder capable of tipping.10.2.2 Perform steps 10.1.2 and 10.1.3.1
40、0.2.3 Tip the holder (if required) until both bonds appear tobe in sharp focus as viewed through the microscope.NOTE 5Care should be taken not to tip the wire bond about thebond-line axis. However, a judgment by eye through the microscope isadequate, as an error of a few degrees will not significant
41、ly alter themeasured pull strength. This tipped-plane method is not consideredapplicable to an optical-electronic or other automatic pull tester.10.2.4 Perform steps 10.1.4-10.1.9.10.3 Method CReferee Method (To be done with a manualpull tester and full operator participation):10.3.1 Measure and rec
42、ord the horizontal distance (d) be-tween the two bonds, the vertical distance (H) between the twobonds, and the loop height (h) as shown in Fig. 2. Use the sameunit of measurement for d, h, and H.10.3.2 Use either Method A or Method B, whichever isappropriate.FIG. 2 Diagram of a Typical Wire BondF45
43、9 13310.3.3 If Method B is used, read and record the tip angle(the angle through which the device has been tipped from thehorizontal) to within 2.11. Calculation (for Method C)11.1 If the substrate was tipped from the horizontal, calcu-late the force in grams-force (or millinewtons) in the wire atfa
44、ilure.11.1.1 If failure occurs at the higher of the two bond sites,calculate the force in the wire as follows:2Fhi5 F11Sd2hD2S11H2hDF12cos1Sh1HdDsinGwhere:Fhi= force in the wire on the high side, gf (or mN),F = corrected applied pull force, gf (or mN),d = horizontal distance between the two bonds al
45、ong aparallel to plane of device,H = vertical distance between the two bond sites along aperpendicular to plane of device,h = loop height as defined in Fig. 2, and = angle through which device has been tipped.11.1.2 If failure occurs at the lower bond site, calculate theforce in the wire as follows:
46、Flo5S11HhDS11H2hD11Fd2 H1h!G2F12cos 2hdsinGwhere Flo= force in the wire at the low side in grams-force(or millinewtons) and the other symbols are as indicated in11.1.1.11.2 If the device was not tipped from the horizontal,calculate Fhiand Floas follows:Fhi5 F11Sd2hD2S21HhDFlo5 FS11HhDS21HhD11Fd2H1h!
47、G2where the symbols have the same meaning as in 11.1.1 and11.1.2.12. Report12.1 Method AThe report for Method A shall contain thefollowing:12.1.1 Name of the person performing the test,12.1.2 Date of the test,12.1.3 Identification of the wire-bond pull tester,12.1.4 Identification of the device,12.1
48、.5 Identification of each wire bond,12.1.6 Corrected force in grams-force (or millinewtons)required to break the wire bond, and12.1.7 Location of failure.12.2 Method BIn addition to that required by 12.1, thereport for Method B shall contain the angle through which thedevice was tipped.12.3 Method C
49、In addition to that required by 12.1, thereport for Method C shall contain the following:12.3.1 Measured values of d, H, and h, in the same units,12.3.2 Angle through which device was tipped, if Method Bwas used, and12.3.3 Calculated force in the wire in grams-force (ormillinewtons).13. Precision and Bias13.1 An interlaboratory evaluation of these test methodswas carried out as follows:13.1.1 Six laboratories participated, including the originat-ing laboratory.13.1.2 Aluminum ultrasonic wedge bonds were used em-ploying Al-1 % Si wire 0.00
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